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Femtosecond time-resolved pump–probe absorption kinetic spectroscopy was used to show that the presence of plasmonic silver nanoparticles in Ag–CuPc hybrid thin-fi lm nanocomposites leads to a significant reduction in the relaxation time of induced absorption from an excited singlet state of copper phthalocyanine fi lm as compared to the pure fi lm. The observed effect is associated with intersystem crossing acceleration in CuPc molecules located in a nonuniform field near the surface of plasmonic silver nanoparticles in the hybrid nanocomposite. The detected effects were demonstrated to depend on the thickness of the copper phthalocyanine layers in the hybrid (Ag–CuPc)nAg nanocomposites. [ABSTRACT FROM AUTHOR]

Lifelogging was introduced as the process of passively capturing personal daily events via wearable devices. It ultimately creates a visual diary encoding every aspect of one's life with the aim of future sharing or recollecting. In this paper, we present LifeSeeker, a lifelog image retrieval system participating in the Lifelog Search Challenge (LSC) for 3 years, since 2019. Our objective is to support users to seek specific life moments using a combination of textual descriptions, spatial relationships, location information, and image similarities. In addition to the LSC challenge results, a further experiment was conducted in order to evaluate the power retrieval of our system on both expert and novice users. This experiment informed us about the effectiveness of the user's interaction with the system when involving non-experts. [ABSTRACT FROM AUTHOR]

We study the electronic excitation dynamics in ensembles of plasmonic gold nanorods (Au NRs), in view of the femtosecond transient absorption spectroscopy, and compare the results with the excitation dynamics of spherical Au nanoparticles (NPs). We use the obtained kinetics of the transient absorption of Au NRs and Au NPs to fit the theoretical profile of the temperature relaxation of the excitation dynamics of electron and lattice nanoparticles, as well as their environment under the excitation by laser pulses with duration of 150 fs. For gold nanorods, the electron–phonon interaction constant reads γNRs = 12 · 1016 W·m−3·K−1, and the heat loss is hNRs = 16 · 108 W·m−2·K−1. In the case of gold nanospheres, the constants are γNPs = 7· 1016 W·m−3·K−1 and hNRs = 8· 108 W·m−2·K−1, respectively. [ABSTRACT FROM AUTHOR]

Manganese ferrite/rice husk-derived activated carbon (MF/AC) was synthesized in a coprecipitation process followed by hydrothermal treatment. The obtained materials were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray mapping (EDX-mapping), vibrating sample magnetometer (VSM), and nitrogen adsorption/desorption isotherms. The MF/AC samples exhibit para-super-magnetic and excellent magnetic properties with high saturation magnetization. The obtained MF/AC was utilized as an electrode modifier for determining methylparaben (MP) in cosmetic products. The pH, amount of modifier, and DPV parameters were investigated to optimize the experimental conditions for the electrochemical process. In the MP concentration range of 14.77–90.91 μM, the peak DPV current exhibits good linearity, with a limit of detection of 4.89 μM and a limit of quantification of 46.55 μM. The data were statistically compared with those obtained from the standard HPLC method. [ABSTRACT FROM AUTHOR]

The formation of plexcitonic nanostructures upon decorating the surface of Ag2S/SiO2 quantum dots with small Au nanoparticles (around 2.0 ± 0.5 nm) is confirmed spectroscopically. It is established via IR spectroscopy that two mechanisms which depend on the charge state of the Au nanoparticle surfaces participate in the adsorption of Au nanoparticles on the surfaces of Ag2S/SiO2 quantum dots. It is shown that the formation of such nanostructures results in a tenfold increase in the luminescence quantum yield of Ag2S/SiO2 quantum dots. [ABSTRACT FROM AUTHOR]

The mechanism of the nonlinear optical response of colloidal solutions of Ag2S quantum dots passivated with thioglycolic acid molecules is considered. Appearance of nonlinear absorption and nonlinear refraction is shown by the Z-scan method using 10-ns pulses of the second harmonic of a Nd:YAG laser. The absorption coefficient dependence was found to saturate with increasing incident radiation intensity. It is suggested that nonlinear absorption occurs with participation of the localized states of structural defects in Ag2S, including the defect luminescence center, which is confirmed by femtosecond transient absorption spectroscopy. A broad structureless transient absorption band is observed in the range of 500–1000 nm, which decays on a time scale of picoseconds. It is concluded that the transient absorption signal is caused by fast (fractions of picoseconds) capture of charge carriers by localized states, which then induce the nonlinear absorption of 10-ns pulses. [ABSTRACT FROM AUTHOR]

In traditional text based medical image retrieval system, it is hard to find visually similar images in large medical image database. Content-based image retrieval is developed to retrieve similar images and it is based on visual attributes describing the content of an image. Developing a method for content based medical image retrieval is a challenging task. This paper proposed a new method for content-based medical image retrieval based on salient regions and deep learning. The proposed method includes two stages: an offline task to extract local object features and an online task for content-based image retrieval in database. In first stage, we extract local object features of medical image depending on shape, texture and intensity, and features extracted by deep learning applied in saliency of decomposition. Secondly, we make online task for content-based image retrieval in database. The user gives query image as an input and the system will retrieve n top most similar images by similarity comparison with bag of code words feature values obtained in the first stage. Evaluation of the proposed method is based on Precision and Recall values. Our dataset includes 5 groups of medical images with their quality varying from low to high. With the best medical image quality group, the accuray can be 91.61% for Precision and 89.61% for Recall. Comparing the average values with others methods, the results of the proposed method are more than 2 to 5% better. [ABSTRACT FROM AUTHOR]

The considered Tractor Trailer Wheeled Mobile Robot (TTWMR) is type of Mobile Robot including a master robot - Tractor and slave robots - Trailers which moves along Tractor to track a given desired trajectory. The main difficulties of the stabilization and the tracking control of TTWMR are due to nonlinear and underactuated systems subjected to nonholonomic constraints. In order to overcome these problems, firstly, we develop the model of TTWMR and transform the tracking error model to the triangular form to propose a control law and an adaptive law. Secondly, the varying time state feedback controllers are designed to generate actuator torques by using Backstepping technique and Lyapunov direct's method, in that these are able to guarantee the stability of the whole system including kinematics and dynamics. In addition, the Babarlat's lemma is used to prove that the proposed tracking errors converge to the origin and the proposed adaptive law is carried on to tackle unknown parameter problem. The simulations are implemented to demonstrate the effective performances of the proposed adaptive law and the proposed control law. [ABSTRACT FROM AUTHOR]